Biotechnology Journal DOI 10.1002/biot.200600139 Biotechnol. J. 2006, 1, 1158–1162 1158 © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Basmati rice belongs to indica group of rice, which con- stitute a small but special group that is considered the best in cooking quality. However, basmati possesses low tillering ability and exhibit yield losses in the same ecosystem under similar cultural practices. Following a transgenic approach, several potentially useful cloned genes can now be introduced into basmati rice for incre- mental improvement of the commercial cultivars. Howev- er, indica rice varieties have generally been less respon- sive to in vitro culture [1, 2]. Likewise, high frequency so- matic embryogenesis with distinct embryo formation has been limited [3]. In the present study an attempt was made to improve somatic embryogenesis and the fre- quency of green plant regeneration in indica type basmati rice varieties by addition of cefotaxime in the callus in- duction and proliferation medium. The antibiotic cefo- taxime (Omnatax TM , C 16 H 16 N 5 O 7 S 2 Na) has been reported to enhance the frequency of plant regeneration in wheat [4], pearl millet [5] and sorghum [6]. This is perhaps the first report describing the beneficial effect of cefotaxime on somatic embryogenesis and subsequent plant regen- eration in indica type basmati rice. Callus cultures were established from mature seed embryos of three indica type basmati rice varieties: Pusa basmati 1, Basmati 370 and Basmati 386. Dehusked healthy seeds after surface sterilization with HgCl 2 (0.1%) for 10 min were rinsed three times with sterile water and aseptically placed on Murashige and Skoog (MS) [7] medi- um supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D; 2.5 mg/L), and 6-furfurylaminopurine (kinetin; 0.5 mg/L). Calli thus obtained were maintained and mul- tiplied through periodic subculturing on two media based on MS salts supplemented with 2,4-D (2.5 mg/l) and kinetin (0.5 mg/L) with (treatment) or without (control) 100 mg/L cefotaxime. Cefotaxime, which is commonly recommended for human injections, was dissolved in sterile water and sterilized by passing through membrane filter (0.2 μm), and was added into molten medium before solidification. The medium without cefotaxime served as control. The cultures were incubated at 25 ± 2°C at 70–80% humidity. Primary and secondary calli cultures were kept in total dark. After 2–3 weeks of incubation, calli showing nodular regions were examined and selected under stereomicro- Short Communication Influence of antibiotic cefotaxime on somatic embryogenesis and plant regeneration in indica rice Deepinder Grewal, Raman Gill and Satbir Singh Gosal Department of Plant Breeding, Genetics and Biotechnology, Punjab Agricultural University, Ludhiana, India An antibiotic, cefotaxime (Omnatax TM ) has been found to promote somatic embryogenesis and subsequent plant regeneration in vitro in indica-type basmati rice cultures. Response was highly genotype specific. The number, mass and morphology of the calli formed on the scutellar tissues were dependent on the growth medium (with or without cefotaxime). The embryogenic nature of nodular calli was confirmed through histological analysis and their plant regeneration ability. The calli of variety Pusa basmati 1 grown on medium supplemented with cefotaxime (100 mg/L) ex- hibited up to 70.5% plant regeneration as compared to control (51.51%). Plants regenerated from emryogenic calli were phenotypically normal and identical to seed-derived plants and exhibited normal fertility. A limited humidity and an optimal aeration of the culture tubes further enhanced the frequency of somatic embryogenesis and plant regeneration. Keywords: Basmati rice · Cefotaxime · Oryza sativa · Shoot proliferation · Somatic embryogenesis Correspondence: Dr. Deepinder Grewal, Department of Plant Breeding, Genetics and Biotechnology, Punjab Agricultural University, Ludhiana 141 004, India E-mail: grewaldeepi@yahoo.co.in Abbreviations: BAP, benzylaminopurine; 2,4-D, 2,4-dichlorophenoxyacetic acid; kinetin, 6-furfurylaminopurine; MS, Murashige and Skoog Received 31 July 2006 Accepted 07 September 2006